N-(aroyl) carbamates and thio carbamates



United States PatentO "'1 is N-(AROYL) CARBAMATES AND v .THIO CARBAMATES Angelo John Speziale, Creve Coeur, and Lowell R. Smith; St; Louis, Mo assignors to Monsanto Company, St. Louis,Mo.,'a'corpoi-atiori of Delaware No DrawinglDriginal application Sept. 4, 1962, Ser.

' Nor221,302. Divided and this application May 13,

H 35 Claims. (Cl. 260-455) i wherein R has the aforedescribedsignificatice and at least one mole of oxalyl'chloride" in the presence of an inert organic-liquid, and thereafter distilling frointhe reactioi'i masssaid aroylisocyaria'te.

A wide range of reaction conditions can be employed in preparing these aroylisocyanates provided the reaction conditionsresult in the evolution of hydrogen chloride which 'is a b y-product of the reaction. In general it is preferable to reflux the reac'tionmixtureand while refluxing to remove the hydrogen chloride as'it forms. Refluxing temperatures in the range cream about 35 f C. to about l''C. havebeen found highly desirable." .With respect to pressure either pressures above or below" atmospheric pressure can be employed, however in general it is satisfactory to employ" atmospheric pressure.

Although theoretically the-"amide reactant and oxalyl chloride .combine in equimolecular amounts to produce the desired isocyanate it is advantageous to employ an excess of oxalyl chlorid,'for example upto about two moles permole of amide.

The inert organic liquid e ployed in the process of this invention will be aliquid-hydrocarbon or a liquid chlorine substituted hydrocarbon or 'rnixture's thereof; e.g. .n+pentane, Ln-hexane; -2-methylpentane, -3'-methylpentane, n-heptane, 2-methylhexane, benzene, toluene,

xylene, cyclohexane, dichloromethane, l,l-dichloroethane, 1,2-dichloroethane, chloroform-carbon tetrachloride, isobutyl chloride, chlorobenzene,. chlorotoluene and mixtures thereofjln general it is preferable that the amount of said inert organic liquid present throughout the courseof the reaction be that at least sufficient to maintain the aroyl isocyanate produced in solution.

The aroylamide reactants of the method of this invention are of the structure R%NH2 wherein R is phenyl, tolyl, xylyl, ethylphenyl, isopropylphenyl, butylphenyl, amylphenyl, chlorophenyl, dichlorophenyl, tn'chlorophenyl, and the various isomeric forms thereof. Illustrative of such are benzoylamide, 3-methylbenzoylamide, 4-isopropyl-benzoylamide, 4-chlorobenphenyl, C 3, alkyl substituted phenyl or zoylamide, 3,4-dichlorobenzoylamide, and 2,4,5-trichlorobenzoylamide. Of these reactants the chlorobenzoylamides of the formula wherein n is a whole number from 1 to 3 upon reacting with oxalyl' chloride in accordance with the process of this invention provide isocyanates of the formula I o1uoflH5-n-'c-N=o='0 which are particularly useful intermediates in organic synthesis. 7 H I Thearoyl isocya'nate s prepared in accordance with the process of this invention are readily hydrolyzecland therefore when stored should be kept free of moisture, as for example stored under refrigerative conditions as.such or dissolved in an inert anhydrous organic liquid.

These isocyanates react with a variety of compounds to provide a large number of useful compounds. For example upon reacting in accordance with this invention equimolecular proportions of an aroyl isocyanate (l) and an aliphatic alcohol or aliphatic mercaptan'of the formula R'XH where X is sulfur or oxygen and wherein R is a C aliphatic radical (e.g. methyl, ethyl, isopropyl, amyl, allyl, butenyLpropynyl, 2-chloroethyl, 2,3- dichlo'ropropyl, 2-chloroallyl, 3-chlorobut-2-enyl, etc.) provides esters of the formula v Illustrative of such carbamates and thiolocarbamates are Methyl N-(3,4-dichlorobenzoyl)carbamate,

which materials are herbicidally active. (2) and a substituted phenol or thiophenol such as the various chlorophenols, chlorothiophenols and nitrophenols provides esters of the formula wherein X is sulfur or oxygen and wherein R" is a phenyl radical having one or more chlorine substituents and/ or nitro substituents, which materials, as for exam- '-"-ple 4-chlorophenyl N-(4-chlorobenzoyl)carbarnate and 4- chlorophenyl N (3,4 dichlorobenzoyl)carbamate, are herbicidally active (3) and either a secondary heterocyclic amine such as morpholine, hexamethyleneimine, piperidine, etc., or a primary or secondary amine of the formula A-NH--B wherein A is hydrogen or a C aliphatic radical (e.g., methyl, ethyl, isopropyl, amyl, allyl, 'butenyl, propynyl, 2-chloroethyl, 2,3-dichloropropyl, 2-chloroallyl, 3-chlorobut-Z-enyl, etc.) or a phenyl radical or an alkyl substituted phenyl radical or a chlorine substituted phenyl radical and wherein B is a C aliphatic radical (e.g., methyl, ethyl, isopropyl, amyl, allyl, butenyl, propynyl, 2-chloroethyl, 2,3'dichloropropyl, 2-chloroallyl, 3-chlorobut-Z-enyl, etc.) or a phenyl radical or an alkyl substituted phenyl radical or a chlorine substituted phenyl radical, provides substituted ureas such as N- 3,4-dichlorobenzoyl -1-aziridine carboxamide N- 3,4-dichlorobenzoyl -4-morpholine carboxamide N-(3,4-dichlorobenzoyl -N- 3',4-dichlorophenyl)urea N-(3,4-dichlorobenzoyl)-N'-isopropyl-N-propynyl urea which materials are herbicidally active.

As illustrative of the method of manufacture of the aroyl isocyanates of this invention and the preparation of useful derivatives thereof is the following:

Example I Example II Employing the procedure of Example I but replacing benzoylamide with an equimolecular amount of 4-isopropylbenzoyl amide there is obtained 4-isopropylbenzoyl isocyanate.

Example III Employing the procedure of Example I but replacing benzoylamide with an equimolecular amount of 3-methylbenzoylamide there is obtained 3-methylbenzoyl isocyariate.

Example IV To a suitable reaction vessel equipped with a thermometer, agitator and refluxcondenser is charged at room tempe'rature82.7 parts by weight of 3,4-dichlorobenzoylamide, 64.0 parts by weight of oxalyl chloride and 266 parts by weight of methylene chloride. The so charged mass is then heated to reflux while agitating then refluxed for 18 hours. Thereafter the resulting mass is subjected to vacuum distillation and the cut (91.0 parts by weight) taken at l05.5 C. at 1.6 mm. of mercury is 3,4-dichlorobenzoyl isocyanate which liquid on standing at room temperature solidified to a white solid.

Example IV-A To a suitable reaction vessel is charged 4.3 parts by weight of 3,4-dichlorobenzoyl isocyanate dissolved in 78 parts by weight of diethylether. While at room temperature and with agitation there is added 2.9 parts by weight of 3,4-dichloroaniline. The precipitate is filtered off and then recrystallized from methanol. The white solid is N (3,4 dichlorobenzoyl)-N'-(3,4-dich1orophenyl) urea, M.P. 202.5203.5 C. This substituted urea is a contact herbicide against broad leaf plants.

4 Example V Employing the procedure of Example IV but replacing 3,4-dichlorobenzoylamide with an equimolecular amount of 2,4,5-trichlorobenzoylamide there is obtained 2,4,5- trichlorobenzoyl isocyanate.

The terminus of the reaction is readily determined by observing the cessation of evolution of hydrogen chloride. In the reaction step between the amide and the oxalyl chloride it is desirable that the inert organic liquid employed have a boiling point below that of the desired isocyanate product. In instances wherein a precipitate forms either in the reaction step or during the distillation operation or any time therebetween it is usually desirable to add suflicient inert organic liquid of any of the aforedescribed types to dissolve the precipitated solids. In recovering the isocyanate product it is preferable to conduct the distillation operation under reduced pressure, e.g., at less than 50 mm. of mercury, and which pressure permits of a distillation temperature of not more than 125 C.

While this invention has been described with respect to certain embodiments it is to be understood that it is not so limited and that variations and modifications thereof obvious to those skilled in the art can be made without departing from the spirit or scope of this invention.

What is claimed is:

1. An N-(aroyl)carbamate of the formula References Cited UNITED STATES PATENTS 4/1964 Harris et al 260552 OTHER REFERENCES Sheeban et al.: .I.A.C.S., pp. 4059-62, vol. 71 (Decem-' ber 1949).

Beilstein: Beilsteins Handbuch der Org. Chemie, 4th

series, vol. 9, p. (1923), QB 251, B4 1918.

Elmore et al.: .J. Chem. Soc. (1956), pp. 4458 and 4462.

CHARLES B. PARKER, Primary Examiner.-

D. R. PHILLIPS, Assistant Examiner. 

1. AN N-(AROYL)CARBAMATE OF THE FORMULA 